adns解析库——域名解析实例（C++、linux）

最新推荐文章于 2021-10-07 23:59:52 发布

转载最新推荐文章于 2021-10-07 23:59:52 发布 · 1.4k 阅读

本文介绍adns库的基本用法，包括初始化、提交域名解析请求、检查解析状态及获取解析结果等步骤，并提供了一个完整的C语言示例程序。

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转自：http://blog.youkuaiyun.com/fty8788/article/details/7480334

adns是一个开源的dns解析库

官方文档：http://www.chiark.greenend.org.uk/~ian/adns/

1. 初始化

adns_state  
 adns;

adns_query  
 query;

adns_answer  
 *answer;

函数原型：

int adns_init(adns_state
 *newstate_r, adns_initflags flags, FILE *diagfile /*0=>stderr*/);

举例：

adns_init(&adns,
 adns_if_noenv, 0);

2. 提交待解析的域名

函数原型：

int adns_submit(adns_state
 ads,

        const char *owner,

        adns_rrtype
 type,

        adns_queryflags
 flags,

        void *context,

        adns_query
 *query_r);

举例：

adns_submit(adns,  
 argv[1],   adns_r_a,  (adns_queryflags) 0,   NULL,   &query);

3. 检测是否有域名已检测完成

函数原型：

int adns_check(adns_state
 ads,

           adns_query
 *query_io,

           adns_answer
 **answer_r,

           void **context_r);

例：adns_check(adns,  
 &query,   &answer,   NULL);

函数原型：

int adns_wait(adns_state
 ads,

          adns_query
 *query_io,

          adns_answer
 **answer_r,

          void **context_r);

例：adns_wait(adns,  
 &query,   &answer,   NULL);

5. 检测是否已完成所有提交的域名的解析

函数原型：

void adns_finish(adns_state
 ads);

例：adns_finish(adns);

6. 范例代码（解析IPv4地址可使用adns v1.2或adns v1.4，解析IPv6地址请使用adns v1.6）

可从此处下载：https://github.com/sunada/adns_example/tree/71c9bf8555b67199c6b94c83027fb71eaa0c0241

#include
 "adns.h"  

#include
 <sys/errno.h>  

#include
 <sys/socket.h>                     

#include
 <netinet/in.h>                       

#include
 <arpa/inet.h>  

int test_dns(char *host)   

{ 

    adns_state
 ads;  

    adns_initflags
 flags;    

    flags
 = adns_if_nosigpipe | adns_if_noerrprint;  

    adns_init(&ads,
 flags, NULL);  

    adns_query
 quer = NULL;  

    adns_submit(ads,
 host, (adns_rrtype) adns_r_a, (adns_queryflags) 0, NULL, &quer);  

    int tryCount
 = -1;  

    int adns_cname
 = 0;  

    while(tryCount
 < 32) {  

        tryCount
 += 1;  

        adns_answer
 *ans;  

        int res
 = adns_check(ads, &quer, &ans, NULL);  

        if(res
 == 0) {        

            if (ans->status
 == adns_s_prohibitedcname) {  

                char cname[128]; 

                strncpy(cname,
 ans->cname, 127);  

                cname[strlen(ans->cname)]
 = '\0';       

                adns_query
 quer = NULL;  

                adns_submit(ads,
 cname, (adns_rrtype) adns_r_addr, (adns_queryflags) 0, NULL, &quer);        

                adns_cname
 = 1;  

            }
else { 

                //resolve
 IPv4 address       

               /*

 * if(adns_cname)  

               *    
 printf("ip: %s\n", ans->status == adns_s_ok ? inet_ntoa(ans->rrs.addr->addr.inet.sin_addr) : "no"); 

               *    
 else  

               *    
 printf("ip: %s\n", ans->status == adns_s_ok ? inet_ntoa(*(ans->rrs.inaddr)) : "no"); 

               */

                //resolve
 IPv6 address

                if(adns_cname){

                    if(ans->status
 == adns_s_ok){

                        char buf[INET6_ADDRSTRLEN];

                        inet_ntop(AF_INET6,
 &ans->rrs.addr->addr.inet6.sin6_addr, buf, sizeof(buf));

                        printf("ip:
 %s\n",
 buf);

                    }

                    else{

                         printf("no\n");

                     }

                 }

                 else{

                     if(ans->status
 == adns_s_ok){

                         char buf[INET6_ADDRSTRLEN];

                         inet_ntop(AF_INET6,
 ans->rrs.in6addr, buf, sizeof(buf));

                         printf("ip:
 %s\n",
 buf);

                     }

                     else{

                          printf("no\n");

                     }

                 }

                 adns_finish(ads); 

                 break; 

            }                   

        }        

        else if (res
 == ESRCH || res == EAGAIN) {  

            sleep(1); 

        }
else { 

            printf("host(%s)
 is err!\n",
 host);  

        } 

    }   

    return 0; 

} 

int main(int argc,
char *argv[])
 {  

    char host[128]; 

    while(1)
 {  

        scanf("%s",
 host);  

        if(strlen(host)
 == 3 && strcmp(host, "eof"))
break; 

        test_dns(host); 

    } 

    return 0; 

}

Makefile

CFLAGS=
 -g  

TARGETS=libadns.a 

LIBOBJS=types.o
event.o
 query.o reply.o general.o setup.o transmit.om parse.o poll.o check.o  

all:
 testdns  

testdns:
 testdns.c libadns.a  

libadns.a:
 $(LIBOBJS)  

                rm
 -f $@  

                $(AR)
 cq $@ $(LIBOBJS)  

clean: 

        rm
 -f $(LIBOBJS) libadns.a *~ config.status  

distclean:
 clean  

        rm
 -f config.h .depend    

$(LIBOBJS):    
 adns.h internal.h
 config.h